Heavy Water Thermodynamic Properties
Reference data and engineering information about heavy water thermodynamic properties for steam and condensate applications.
Overview
Engineering reference data for Heavy Water Thermodynamic Properties in steam condensate.
Key Formulas
Steam Quality
Mass fraction of vapor in two-phase mixture.
Enthalpy of Wet Steam
Specific enthalpy of wet steam.
Flash Steam
Steam generated when condensate flashes to lower pressure.
Condensate Load
Condensate generated by heat transfer.
Variables
| Symbol | Description | Unit |
|---|---|---|
| Steam quality | — | |
| Enthalpy of saturated liquid | kJ/kg | |
| Latent heat of vaporization | kJ/kg | |
| Specific enthalpy | kJ/kg | |
| Heat transfer rate | kW |
Thermodynamic Properties of Heavy Water
Heavy water (D₂O) exhibits distinct thermodynamic properties compared to normal water (H₂O), primarily due to the greater mass of deuterium. This influences molecular bonding strength and vibrational frequencies, leading to higher boiling and melting points, increased viscosity, and altered latent heats.
Key Physical Constants & Properties
The following table summarizes the fundamental thermodynamic properties of D₂O at specified conditions.
Property | Value | Unit | Condition |
|---|---|---|---|
| Molar Mass | 20.02751 | g/mol | - |
| Boiling Temperature | 101.4 | °C | 101.325 kPa |
| Melting Temperature | 3.81 | °C | 101.325 kPa |
| Triple Point Temperature | 3.82 | °C | 0.00661 bar |
| Critical Temperature | 370.697 | °C | - |
| Critical Pressure | 220.98 | bar | - |
| Critical Density | 0.356 | g/cm³ | - |
| Maximum Density | 1105.9 | kg/m³ | 11.23 °C |
| Latent Heat of Evaporation | 2073.2 | kJ/kg | 101.4 °C |
| Latent Heat of Fusion | 306.2 | kJ/kg | - |
| Specific Heat (Cₚ) | 4.219 | kJ/(kg·K) | 20 °C |
| Viscosity | 1.251 | cP (mPa·s) | 20 °C |
| Surface Tension | 71.87 | dyn/cm | 25 °C |
| Ionization Constant (pKw) | 14.951 | - | 25 °C |
Source: engineeringtoolbox.com
Important Definitions and Explanations
- Triple Point: The unique temperature and pressure at which all three phases (solid, liquid, and vapor) of a substance coexist in thermodynamic equilibrium. For D₂O, this occurs at 3.82 °C and 661 Pa.
- Critical Point: The temperature and pressure above which a substance's liquid and gas phases become indistinguishable. It defines the endpoint of the liquid-vapor phase boundary.
- Ionization Constant (pKw): For water, this represents the equilibrium constant for its self-ionization (). A higher pKw (14.951 for D₂O vs. ~14.00 for H₂O at 25°C) indicates a lower degree of ionization.
- Specific Heat (Cₚ): The amount of heat energy required to raise the temperature of one unit mass of a substance by one degree at constant pressure. The value for D₂O is slightly lower than that for H₂O.
- Bulk Modulus Elasticity: A measure of a substance's resistance to uniform compression. It is defined as the ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume.